<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <div id="app">
    <div :style="sty"></div>
    <div :style="{width:100+300+500+'px',height:2>3?'100px':'500px',background:'skyblue'}"></div>
  </div>
  <script src="./vue.js"></script>
  <script>
    const vm = new Vue({
      el:"#app",
      data: {
        sty:{
          width: '200px',
          height: '300px',
          background: 'blue'
        }
      }
    })
  </script>
</body>
</html>